Method is known of manufacturing filters and similar porous sintered bodies from stainless steel powder. The basis taken there was powder with irregular powder shape which gave the green body the requisite strength in that the individual powder granules engage with each other prior to final sintering. From the viewpoint of filtering for example, the irregular shape of the granules is however a disadvantage in that they render manufacture of a tailor-made material which is subject to requirements with regard to, for example, bore volume, back-pressure, etc., difficult or impossible.
If a well-defined geometric shape is imparted to the powder, in actual practice a spherical shape, and if the powder is screened to give a certain particle size distribution, it is possible to calculate in advance the pore volume and similar properties of the sintered body in those cases where the product is manufactured by loose sintering. Whilst conventionally-employed powders of ferritic or austenitic stainless steel with irregular powder shapes have given a good bond during cold pressing, spherical powders from the same steel have however proved to be extremely difficult to compress i.e. they exhibited extremely low green strength and hence could not be cold-pressed and sintered in the conventional manner.